Tuberculosis Skin Test (PPD Skin Test)

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Tuberculosis skin test facts

The tuberculosis skin test is also known as the tuberculin test or PPD test.

The PPD test is used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB).

The standard recommended tuberculin test is the Mantoux test, which is administered by injecting a 0.1 mL of liquid containing 5 TU (tuberculin units) PPD (purified protein derivative)into the top layers of skin of the forearm.

Skin tests should be read 48-72 hours after the injection.

The basis of the reading of the skin test is the presence or absence and the amount of induration (localized swelling).

A negative test does not always mean that a person is free of tuberculosis.

A person who received a BCG vaccine (administered in some countries but not the U.S.) against tuberculosis may also have a positive skin reaction to the TB test.